A 4-month-old infant was referred to the pediatrics neurology clinic with macrocephaly. Her neurological status was normal. Sonography, magnetic resonance imaging (MRI) and angiography revealed a large vein of Galen aneurysmal malformation (VGAM) (Figure 1). The patient was treated endovascularly, using ethylene-vinyl alcohol copolymer (Onyx) as an embolic agent. Occlusion of the feeding arteries was complete, and there was no remaining flow into the VGAM (Figure 2). Follow-up MRI after 1 year showed that hydrocephalus persisted, whereas the VGAM had shrunk (Figure 2). The patient had development delay and seizures.